The relation between a number of potential risk factors and change in body mass index per semester was examined in a community-based cohort of 1,809 homosexual and bisexual men seropositive for human immunodeficiency virus type 1 (HIV-1).

The men were followed semiannually for up to 6.5 years between 1984 and 1990.

A total of 9,735 person-semesters of observations were available for analysis.

A Markov-type autoregressive model, adjusting for previous body mass index, was used to predict the change in body mass index over each person-semester.